Stress Relaxation in Al-Si-Cu Thin Films and Lines

1994 ◽  
Vol 356 ◽  
Author(s):  
A. Witvrouw ◽  
J. Proost ◽  
B. Deweerdt ◽  
Ph. Roussel ◽  
K. Maex
Keyword(s):  
Thin Films ◽  
Activation Energy ◽  
Flow Stress ◽  
Stress Relaxation ◽  
Relaxation Data ◽  
Cu Films ◽  
Dislocation Glide ◽  
Average Activation Energy ◽  
Curvature Measurements ◽  
Substrate Curvature

AbstractSubstrate curvature measurements were used to study stress relaxation in Al-Si-Cu films at temperatures between 45 and 165 °C. Dislocation glide with an average activation energy, resp. athermal flow stress of 1.7 ± 0.2 eV, resp. 600 ± 200 MPa could describe the relaxation data for temperatures up to 120 °C well. Stress relaxation at 92 °C was found to progress much slower in 1 μm wide nitride passivated lines than in thin films or unpassivated lines.

Stress Relaxation in Al–Cu and Al–Si–Cu Thin Films

1999 ◽  
Vol 14 (4) ◽  
pp. 1246-1254 ◽  
Author(s):  
A. Witvrouw ◽  
J. Proost ◽  
Ph. Roussel ◽  
P. Cosemans ◽  
K. Maex
Keyword(s):  
Stress Relaxation ◽  
Thermal Cycling ◽  
Thermal Cycle ◽  
Room Temperature ◽  
Relaxation Data ◽  
Cu Films ◽  
Dislocation Glide ◽  
Transmission Electron ◽  
Stress Changes ◽  
Curvature Measurements

Substrate curvature measurements were used to study stress changes during thermal cycling and isothermal tensile stress relaxation in 800 nm Al–0.5 wt% Cu and Al–1 wt% Si–0.5 wt% Cu films. For both compositions dislocation glide can describe the relaxation data well for temperatures up to 120 °C for Al–Si–Cu and up to 100 °C for Al–Cu. The average activation energy for Al–Si–Cu and Al–Cu is 1.7 ± 0.2 eV and 3.0 ± 0.3 eV, respectively. The athermal flow stress is the same for both and equal to 600 ± 200 MPa. This result is consistent with the obstacles for glide being Al2Cu precipitates, which, in the case of Al–Si–Cu, are fine and can be cut by the dislocations, and, in the case of Al–Cu, are strong and provide Orowan strengthening. Also, the stress changes during thermal cycling in the Al–Cu films are different from those in the Al–Si–Cu films. For Al–Cu films, the room temperature stress decreases after each thermal cycle, while for Al–Si–Cu stress changes during thermal cycling are stable from the second cycle on. These observations are supported by thorough transmission electron microscopy (TEM) studies.

Mechanisms of Inelastic Deformation and Stress Relaxation in Thin Metallizations Bonded to Hard Substrates

1991 ◽  
Vol 226 ◽  
Author(s):  
M.A. Korhonen ◽  
P. Bergesen ◽  
Che-Yu Li
Keyword(s):  
Thin Films ◽  
Stress Relaxation ◽  
Integrated Circuits ◽  
Large Scale ◽  
Effective Means ◽  
Grain Boundary Sliding ◽  
Dislocation Creep ◽  
Dislocation Glide ◽  
Constrained Deformation ◽  
Hard Substrates

AbstractThe yield strength of metallic thin films bonded to hard substrates can be significantly higher than is customary for bulk samples of the same metal. This is related to the constrained nature of the deformation. The constrained deformation, as well as the commonly observed crystallographic texture of thin films, places restrictive conditions on the mechanisms of deformation that produce stress relaxation. In narrow aluminum based metallizations used as interconnects in large scale integrated circuits thermal stress induced voiding provides an effective means for stress relaxation. For these interconnects, the stress state is tensile after excursions to higher temperatures; the stresses relax mainly by dislocation glide and grain boundary sliding during the cooldown, while the longer term relaxation is governed by stress-induced voiding and dislocation creep.

Stress and Microstructural Evolution of Lpcvd Polysilicon Thin Films During High Temperature Annealing

1996 ◽  
Vol 441 ◽  
Author(s):  
Chia-Liang Yu ◽  
Paul A. Flinn ◽  
Seok-Hee Lee ◽  
John C. Bravman
Keyword(s):  
Thin Films ◽  
High Temperature ◽  
Stress Relaxation ◽  
Deposition Temperature ◽  
Stress Generation ◽  
Deformation Model ◽  
Silicon Thin Films ◽  
Compressive Stresses ◽  
Polysilicon Films ◽  
Curvature Measurements

AbstractThe mechanisms of stress generation and stress relaxation of LPCVD silicon thin films were studied using high temperature wafer curvature measurements. The stresses generated during depositions are measured as functions of deposition temperature and microstructure. Amorphous silicon deposited with a compressive stress shows a large stress change toward tensile during crystallization. The stress relaxation of polysilicon films deposited with tensile stresses can be described by a deformation model from Ashby and Frost [1]. The polysilicon films deposited with compressive stresses have hydrogen incorporated during deposition and shows hydrogen evolution during thermal cycles.

Plastic properties of thin films on substrates as measured by submicron indentation hardness and substrate curvature techniques

1986 ◽  
Vol 1 (6) ◽  
pp. 845-851 ◽  
Author(s):  
M.F. Doerner ◽  
D.S. Gardner ◽  
W.D. Nix
Keyword(s):  
Thin Films ◽  
Plastic Deformation ◽  
Film Thickness ◽  
Indentation Hardness ◽  
Silicon Substrates ◽  
Strengthening Effect ◽  
Plastic Properties ◽  
Aluminum Films ◽  
Curvature Measurements ◽  
Substrate Curvature

Substrate curvature and submicron indentation measurements have been used recently to study plastic deformation in thin films on substrates. In the present work both of these techniques have been employed to study the strength of aluminum and tungsten thin films on silicon substrates. In the case of aluminum films on silicon substrates, the film strength is found to increase with decreasing thickness. Grain size variations with film thickness do not account for the variations in strength. Wafer curvature measurements give strengths higher than those predicted from hardness measurements suggesting the substrate plays a role in strengthening the film. The observed strengthening effect with decreased thickness may be due to image forces on dislocations in the film due to the elastically stiffer silicon substrate. For sputtered tungsten films, where the substrate is less stiff than the film, the film strength decreases with decreasing film thickness.

Mechanisms of Inelastic Deformation and Stress Relaxation in Thin Metallizations Bonded to Hard Substrates

1991 ◽  
Vol 225 ◽  
Author(s):  
M. A. Korhonen ◽  
P. Brørgesen ◽  
Che-Yu Li
Keyword(s):  
Thin Films ◽  
Stress Relaxation ◽  
Integrated Circuits ◽  
Large Scale ◽  
Effective Means ◽  
Grain Boundary Sliding ◽  
Dislocation Creep ◽  
Dislocation Glide ◽  
Constrained Deformation ◽  
Hard Substrates

ABSTRACTThe yield strength of metallic thin films bonded to hard substrates can be significantly higher than is customary for bulk samples of the same metal. This is related to the constrained nature of the deformation. The constrained deformation, as well as the commonly observed crystallographic texture of thin films, places restrictive conditions on the mechanisms of deformation that produce stress relaxation. In narrow aluminum based metallizations used as interconnects in large scale integrated circuits thermal stress induced voiding provides an effective means for stress relaxation. For these interconnects, the stress state is tensile after excursions to higher temperatures; the stresses relax mainly by dislocation glide and grain boundary sliding during the cooldown, while the longer term relaxation is governed by stress-induced voiding and dislocation creep.

The Effect of the Passivation Material on the Stress and Stress Relaxation Behavior of Narrow Al-Si-Cu Lines

1996 ◽  
Vol 436 ◽  
Author(s):  
A. Witvrouw ◽  
P. Flinn ◽  
K. Maex
Keyword(s):  
Stress Relaxation ◽  
Temperature Dependence ◽  
Room Temperature ◽  
Relaxation Behavior ◽  
Storage Test ◽  
Stress Relaxation Behavior ◽  
Passivation Film ◽  
Parallel Lines ◽  
Curvature Measurements ◽  
Substrate Curvature

Abstract800 nm thick and 1μm wide Al-1wt.%Si-0.5wt.% Cu parallel lines with 1 μm spacing were passivated with PECVD oxide, oxynitride or nitride. Substrate curvature measurements as a function of temperature and XRD-measurements at room temperature were used to characterize macroscopic samples of these parallel Al-Si-Cu-lines. By using both techniques the average inplane stresses for the Al-Si-Cu lines as well as for the covering passivation material can be determined as a function of temperature. The highest and lowest stresses in the Al-Si-Cu are observed for lines with nitride and oxide passivations, respectively. Also the number of voids in the lines after a storage test at 250 °C is clearly highest for a nitride passivation and lowest for an oxide passivation.The stress in the passivation itself and its temperature dependence is found to be very different from the stress in a blanket passivation film.

The Effect of the Passivation Material on the Stress and Stress Relaxation Behavior of Narrow Al-Si-Cu Lines

1996 ◽  
Vol 428 ◽  
Author(s):  
A. Witvrouw ◽  
P. Flinn ◽  
K. Maex
Keyword(s):  
Stress Relaxation ◽  
Temperature Dependence ◽  
Room Temperature ◽  
Relaxation Behavior ◽  
Storage Test ◽  
Stress Relaxation Behavior ◽  
Passivation Film ◽  
Parallel Lines ◽  
Curvature Measurements ◽  
Substrate Curvature

Abstract800 nm thick and 1 jim wide Al-lwt.%Si-0.5wt.% Cu parallel lines with I μm spacing were passivated with PECVD oxide, oxynitride or nitride. Substrate curvature measurements as a function of temperature and XRD-measurements at room temperature were used to characterize macroscopic samples of these parallel Al-Si-Cu-lines. By using both techniques the average inplane stresses for the Al-Si-Cu lines as well as for the covering passivation material can be determined as a function of temperature. The highest and lowest stresses in the Al-Si-Cu are observed for lines with nitride and oxide passivations, respectively. Also the number of voids in the lines after a storage test at 250 °C is clearly highest for a nitride passivation and lowest for an oxide passivation.The stress in the passivation itself and its temperature dependence is found to be very different from the stress in a blanket passivation film.

Determination of Elastic Constants and Viscosity of Amorphous Thin Films From Substrate Curvature

1990 ◽  
Vol 188 ◽  
Author(s):  
Ann Witvrouw ◽  
Frans Spaepen
Keyword(s):  
Thin Films ◽  
Viscous Flow ◽  
Elastic Constants ◽  
Activation Enthalpy ◽  
Amorphous Thin Films ◽  
Curvature Measurements ◽  
Substrate Curvature

ABSTRACTSubstrate curvature measurements were used to monitor viscous flow in Pd79Si21 films at temperatures between 100 and 250°C. To determine the viscosity and the change in viscosity the elastic constants of the film were measured by depositing films on pre-bent substrates: E = 10 ± 1 1010 Pa and ν = 0.43 ± 0.04 The activation enthalpy for η is 13 ± 1 kJ/mole.

Line width Dependence of Stress Relaxation and Yield Behavior of Passivated Al(Cu) Lines

1994 ◽  
Vol 338 ◽  
Author(s):  
I.-S. Yeo ◽  
S.G.H. Anderson ◽  
C.-N. Liao ◽  
D. Jawarani ◽  
H. Kawasaki ◽  
...  
Keyword(s):  
Stress Relaxation ◽  
Void Formation ◽  
Relaxation Behavior ◽  
Effect Of Temperature ◽  
Thermally Induced ◽  
Stress Relaxation Behavior ◽  
Cu Films ◽  
Dislocation Glide ◽  
Thermally Activated ◽  
On Line

ABSTRACTStress relaxation behavior of thermally induced stresses in passivated line structures is strongly influenced by the metal yield strength. For some line geometries, stress relaxation can lead to void formation. In this study, bending beam measurements have been carried out to measure the thermal stress and stress relaxation behavior of passivated Al(l wt.% Cu) line structures with 3, 1, and 0.5 µm line widths. Our results reveal that stress relaxation in Al(Cu) films and lines shows log(time) kinetics consistent with a thermally activated dislocation glide mechanism. The kinetics of stress relaxation depend on line geometry and temperature, which can be explained by a combined effect of temperature (mass transport) and shear stress (driving force).

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